Baler and method of baling

ABSTRACT

A baler apparatus includes a baling chamber including at least one adjustable wall for adjusting compression of a body of bale material. A reciprocating plunger is operable to compress the bale material and a binding device binds the compressed material to form a bale by use of twine loops. An adjustment mechanism increases as a length of outer twine loops when binding the bale relative to the inner twine loops, to reduce compression within part of the body of bale material and avoid twine breakage that can otherwise occur as a bale is ejected from the baler.

The present invention relates to a baler and a method of baling, in particular but not exclusively for baling an agricultural crop.

BACKGROUND TO THE INVENTION

For efficient transport and storage, and to improve the keeping properties of the product, agricultural products like hay, straw and silage may be compressed into bales of a parallelepiped shape, which are known as ‘square’ bales. After the compression of the bale material the shape and the compression of the bale is maintained by binding the bale with twines that are looped around the compressed bale material. The ends of the twine are then knotted together.

Typically, compression of the bale material is performed by a reciprocating plunger press baler. A typical baler of this type is described in U.S. Pat. Nos. 4,074,623 and 4,142,746 to Hesston Corporation. This baler machine includes a baling chamber comprising an open-ended channel through which bale material is forced by a reciprocating plunger. The plunger is driven in a substantially linear direction between two end positions comprising respectively a withdrawn position in front of the baling chamber and an extended position in which it extends into the baling chamber. When the plunger is in the withdrawn position the baling chamber is loaded with the bale material to be compressed. The plunger is then driven into the baling chamber so that this new material is compressed against a body of compressed material already in the baling chamber. Any newly compacted material that is added to the already compacted material in the chamber is called a ‘wad’. The friction of the compressed material with the walls of the baling chamber provides a resistive force allowing for compression of the new material that is introduced into the baling chamber in front of the plunger.

After compression, the newly compressed material and the compressed material already in the baling chamber are moved together towards the outlet end of the channel until the plunger reaches its fully extended end position. The plunger then moves in the opposite direction toward its withdrawn position so that the baling chamber can be reloaded with new material to be compressed.

The friction within the baling chamber between the already formed bale and the walls of the channel can be regulated for instance by pressing the side walls and/or the top panels of the baling chamber against the compressed material with different levels of force.

The bale is held in compression after leaving the machine by binding the bale with twines that are tied around the body of compressed material. In some machines, a single spool process is used in which each binding is formed with twine that is taken from a single spool and looped around the entire circumference of the bale, then tied with a single knot. Such a process is described in U.S. Pat. No. 3,895,571, which includes a mechanism for releasing the tension in the twine during knotting so as to avoid problems while knotting the twine.

Another example of a machine that uses a single spool process is described in EP0392627A. This machine includes a mechanism for reducing the bale pressure at the start of the bale forming process to allow the binding twine to slide more easily between the bale material and the previously formed bale that is still in the baling chamber.

Another machine that uses a single spool process is described in DE4031695A. This machine includes a mechanism for reducing the bale pressure at the start of the twine knotting process to allow the binding twine to be knotted more easily.

Other baling machines use a twin spool process in which each binding is formed using twines from two spools, which are tied with two knots at opposite ends of the bale. One advantage of the twin spool process is that the bale can be compressed to a higher compaction pressure because the twine does not have to be passed between the newly compacted bale and the previously formed bale. However, this increased compacting pressure also increases the risk of the twines breaking when the bale is ejected from the baling chamber. The twin spool binding process will now be described in more detail.

At the start of the baling process two lengths of twine from spools on opposite sides of the baling chamber are connected to one another by tying the ends of the twines together.

As the bale material is compacted in the baling chamber the spools feed twine to the baling chamber on either side of the bale material. On one side of the baling chamber the twine passes through the tip of a baling needle. When the body of bale material has reached its full length, between two successive compressing strokes, the needle brings the twine as a loop to the other side of the baling chamber. A knotter device then knots the twine, joining an end of the twine loop that was brought around the compressed bale by the needle to an end of the twine that was supplied by the spool on other side of the baling chamber (on the same side as the knotter). A second knot is also formed for the start of the next bale. The needle is then retracted and a new bale is started.

The pressure applied to the material in the baling chamber during the compression stroke is typically 3 to 4 bar for a bale with a typical compression surface of 90*120 cm. The knotted twine used in this type of baling machine typically has a breaking strength of 200 kgf. Six knotted twines can therefore hold about 6*2*200=2400 kgf. In a conventional bale with a compression surface of 90*120 cm this results in a holding pressure of only 0.22 bar. This places an upper limit on the compression pressure that can be applied to the bale. If a higher compression level is to be maintained, more binding twines have to be used.

There is generally some expansion of the bale as it is ejected from the channel of the baling chamber and this expansion has to be taken into account when designing the baling machine to ensure that the twines are able to maintain the compression of the bale without breaking. However, the amount of expansion is not uniform. Some materials such as dry straw and grass are more elastic than others and tend to expand more. There is therefore a greater risk that the twines will break when baling such materials.

To reduce the risk of breakage when baling highly elastic bale materials, in praxis the overall compression level is sometimes reduced. However, this reduces the density and mass of the bale, which is generally undesirable.

Alternatively, the twine loops tied around the compressed material can be made by design slightly longer than the circumference of the compressed bale while it is in the baling chamber. Then, when the bale leaves the baling chamber it expands to a size determined by the slightly greater length of the twine. Due to this expansion, the pressure in the bale falls to a value that can be withstood by the twines. However, this also has a negative impact on the mass and density of the bale and it results in a lower level of compression for all materials, including less elastic materials for which a lower level of compression is not needed.

Recently, the compression level that can be produced by baling machines that use the twin spool process has increased to typically about 6-10 bar, but the holding strength of the twine has hardly improved. The increased compression level places greater stress on the baling twines, particularly when binding materials that are relatively elastic, for example dry grass. We have found that with some materials and/or in certain weather conditions the pressure after expansion of the bale can be higher than the twines can withstand. As a result, we have found that the twines can break and the bales can then burst during or after leaving the baling chamber. Furthermore, because the twines near the edges (outermost sides) of the bale have to withstand more force due to the fact that there is more material to hold, there is more tension on the outer twines than on the inner twines. When bales expand too much upon ejection the outer twines will tend to burst first, especially the outer twines.

Attempts to reduce the problem described above have been described in U.S. Pat. No. 4,577,553 which includes a mechanism for increasing the length of the twine loops so that they are less likely to burst, particularly when using sisal twine. However this invention does not describe any possibility to adjust the increase of loop length in relation to the expansion of the material. Furthermore, it is complicated and not reliable since the hook for pulling extra twine length has to grab the twine from the bale, while the position of the twine on the bale can vary widely.

Another attempt to address the problem is described in WO 2013017229. In praxis it shows that this method under certain field and material conditions is difficult to adjust and gives poorly shaped bale ends and sometimes overly dense bales because the last part of the bale is compressed at a lower level.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a baler and a method of baling that mitigate the problems identified above and, in particular, that allow optimum and constant compression of all bale materials and compensate for differences in the elasticity of those materials, while reducing the risk of twine breakage.

According to one aspect of the present invention there is provided a baler apparatus including a baling chamber comprising a channel having an inlet end and an outlet end, a reciprocating plunger adjacent the inlet end of the baling chamber that is operable to compress a body of bale material within the baling chamber, and a binding device for binding the compressed body of bale material to form a bale, wherein the baling chamber has at least one adjustable wall for adjusting the compression of the body of bale material by controlling the pressure applied to the body of bale material during formation of a bale, the apparatus being further provided with means for increasing the length of at least the outer twine loops, relative to the inner twine loops of the bale at binding, to reduce the tension in twines on the outer part of the body of bale material.

By increasing the loop length of the outer twines relative to the inner twines at least just before and during the knotting process, the tension of the outer binding twine after the bale leaves the baling chamber can be reduced and/or equalled to the tension in the inner binding twines, thereby reducing the risk of breakage if the bound bale expands either on leaving the baling chamber or subsequently. Preferably the difference of twine loop length between outer and inner twines can then be controlled according to the nature of the bale material. For example, the difference of twine loop length can be greater if the bale is made of relatively elastic material such as dry grass, or lower if the bale is made of less elastic material.

The bale weight and density can therefore be maintained at a high level, without increasing the risk of the bale bursting and without reducing the compression force in the last part of the bale.

Preferably the increase of loop length in the outer twines relative to the inner twines is formed by guiding the twine over an adjustable roller or guide at the top part of the bale, preferably near to the knotting device. Such an arrangement is a simple design with no active elements, i.e. passive parts that have little risk of malfunctioning.

According to the invention, the increase of the individual twine loops can be adjusted per twine loop. Particularly, the outermost twines more to the left and right side of the bale are configured to have more loop length as these twines will have to withstand more expansion force than the ones in the middle of the bale. Preferably this extra loop length increase is 1-3 cm relative to the inner twines.

Preferably the length of the second-most outer twine loop could be increased to a lesser value, preferably 1-2 cm, as the outer twine loops. This to fully equal the tension of all twine loops.

Preferably the roller/guide for increasing the loop length is easily displaceable/removable for servicing the knotter and for re-routing the twine after breakage of a twine.

Preferably the roller/guide for increasing the loop length is fixedly but adjustably connected to the baler.

Preferably the increase of the loop length can be achieved by positioning the knotting device of the outer twine loops relatively further from the bale when the twine loop is formed. This arrangement is advantageous because no extra parts are required that could obstruct the material flow.

According to another aspect of the invention there is provided a method of baling bale material in a baler apparatus having a baling chamber including a channel with an inlet end and an outlet end, a reciprocating plunger adjacent the inlet end of the baling chamber, and a binding device, the method comprising activating the reciprocating plunger to compress a body of bale material in the baling chamber and use of at least one adjustable means for increasing the twine loop length of at least the outer two twine loops relative to the inner twine loops, at least during the closing of the loop, to form a bale. The twine loop length can be determined as a function of the bale material and associated conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view showing the main components of a baling machine;

FIG. 2a is a schematic illustration plan view of a prior art baling machine during compression of the bale material;

FIG. 2b is a schematic illustration plan view of the prior art baling machine after withdrawal of the plunger and prior to binding of the bale material;

FIG. 3a is a schematic illustration of a prior art bale bound with baling twine, before the ends of the twine are tied;

FIG. 3b is a schematic illustration of the prior art bale, after the ends of the baling twine are tied;

FIG. 3c is a schematic illustration of the prior art bale after the bale has expanded, causing breakage of the baling twine;

FIGS. 4a to d are schematic illustration of a baling machine according to an embodiment of the invention during closing of the twine loop;

FIGS. 5 and 5 b shows the device incorporated in the design of a baler.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The baling machine or baler shown in FIG. 1 includes a baling chamber 2 that is defined by top and bottom plates 3 and two side walls 4, one of which has been omitted from the drawing to show the interior of the chamber 2. The baling chamber 2 comprises a channel having an inlet end 6 and an outlet end 8. At the inlet end 6, the channel is closed by a plunger 10 that can be driven into the baling chamber 2 in a reciprocating manner. In this example, the plunger 10 is driven from a rotating drive axle 12 via a pair of drive arms 14, 16. The baling machine also includes a binding device 17, for example as described in U.S. Pat. No. 4,074,623, for binding the bale with binding twine.

In addition, the baling machine includes a pick up mechanism A for picking up cut bale material (for example grass and straw) from the ground, a feed mechanism B for feeding the bale material into the baling chamber 2, a set of needles C for feeding binding twine through the baling chamber and a drive mechanism D for transmitting drive to the drive axle 12 from the drive output of a towing vehicle (not shown). These components are all conventional and so will not be described in detail.

The prior art baling machine represented schematically in FIGS. 2a and 2b is substantially as described in U.S. Pat. No. 4,074,623, the contents of which are understood by a skilled person and incorporated herein by reference. The baling machine includes a baling chamber 2 that is defined by two side walls 4, as well as by top and bottom plates (not shown in FIGS. 2a and 2b , but denoted 3 in FIG. 1). The opposed side walls 4 are inclined towards one another to provide a tapered channel and can be adjusted to different degrees of taper. The baling chamber 2 thus consists of a channel having an inlet end 6 and an outlet end 8. At the inlet end 6, the channel is closed by a plunger 10 that can be driven into the baling chamber 2 in a reciprocating manner. In this example, the plunger 10 is driven from a rotating drive axle 12 via a pair of drive arms 14, 16.

The baling machine of FIGS. 2a and 2b is shown in operation, containing within the baling chamber 2 a compressed but unbound body 18 of bale material and a compressed and bound bale 20. The completed bale 20 is bound with binding twine 22. In this example, five loops of binding twine 22 are used, which extend around the top, bottom, front and rear faces of the bale 20.

In FIG. 2a the baling machine is shown during a compression stroke, in which the plunger 10 is driven forwards as depicted by arrows 24 into the baling chamber 2. As a result of this movement of the plunger 10, a body 18 of bale material that has been loaded into the baling chamber 2 is driven forwards within the baling chamber 2 against the end face of the already formed bale 20. The body 18 of bale material is thus compressed both longitudinally and transversely: longitudinal compression resulting from being pressed by the plunger 10 against the end face of the already formed bale 20 (and from the frictional forces acting on the bale 20), and transverse compression of the body 18 resulting from it being forced between the converging side walls 4. The frictional force on the body 18 of bale material can be regulated by adjusting the positions of the side walls 4 and/or the top and bottom plates as indicated by arrows 30.

During compression, the front and rear faces 25 a, 25 b of the body 18 of bale material are driven forwards by the plunger 10 as depicted by the arrows 26, 28. The resulting compression of the bale material is indicated by diagonal arrows 32. This process is repeated until the body 18 of bale material has reached the required size.

Once the body 18 of bale material has reached the required size, the bale material is bound with baling twine. A set of needles (not shown in FIGS. 2a and 2b , but denoted C in FIG. 1) carrying the binding twines are extended through slots 34 in the face of the plunger 10 and the twines 22 are then tied around the bale. The binding and knotting processes may for example be substantially as described in U.S. Pat. No. 4,074,623.

After the bale material has been bound, the plunger 10 withdraws as illustrated by arrows 35 in FIG. 2b so that bale material for the next bale can be fed into the baling chamber. As the plunger withdraws, the rear face 25 b of the body 18 of bale material recovers slightly and expands a short distance rearward as depicted by arrows 36. This rearward expansion of the body 18 of bale material is limited by the binding twines 22 that have been tied around the body 18 of bale material and increases the tension in the binding twines.

The next bale is then formed by introducing bale material into the gap 37 between the plunger 10 and the rear face 25 b of the bale that has just been formed, then compressing the material by reciprocating movement of the plunger 10. This process is repeated as necessary to increase the size of the compressed body of bale material. As the process is repeated, the bale 20 that has just been formed is pushed along the channel towards the downstream end 8 of the baling chamber 2, and the previously formed bale 20′ is ejected from the downstream end of the baling chamber 2 onto the ground.

When the bale 20′ is ejected from the baling chamber the compressive forces acting on the front and rear faces of the bale are removed, allowing the bale 20′ to expand against the tension of binding twines 22. The overall length of the bale 20′ therefore increases slightly, the unexpanded size of the bale 20′ being indicated by broken lines 38. This increases the tension in the twines 22. As a result of this partial decompression of the bale the load carried by the twines 22 as the bale is expelled from the baling chamber 2 is significantly less than the pressure that was applied to the bale material by the plunger 10 (for example about 0.22 bar as compared to a compacting pressure of 4-10 bar).

The prior art binding process is illustrated again in FIGS. 3a to 3c . In FIG. 3a , the bale 20 is shown in a compressed state, with two twines 22 a, 22 b forming a loop around the bale. First ends of the twines have been tied together forming a first knot 40. The second ends 22 a′, 22 b′ of the twines have not yet been tied together.

In FIG. 3b the bale 20 is shown after the second ends of the twines 22 a, 22 b have been tied together forming a second knot 40′. An extra length L of twine is required by the knotting device, which is released after the knot 40′ has been tied. Therefore, when both ends of the twine are released from the knotting device the total length of the twine binding increases by L1+(L3−L2), which slightly reduces the tension in the binding.

When the bale 20 is ejected from the baling chamber, both ends of the bale expand by a distance e as shown in FIG. 3c , the original positions of the ends of the bale being depicted by broken lines 38. This causes the circumference of the bale to increase by a length of 4*e. If the increase in circumference is greater than the additional length of twine released by the knotting device, that is if 4*e>L1+(L3−L2), the overall tension in the twine binding will increase, which may result in failure of the twine forming the binding at knot 40′ or 40.

As is shown in FIG. 2b the twines most to the side of the bale (referred to herein as “outermost”) have to withstand a bigger part of the expanding bale (½Z+X) compared to the twine loops around the middle of the bale (2*½Z). Therefore the tension of the outer twine loops tends to be higher than the inner twine loops. It is observed that when breakage of the twine loops occur that in most of the cases the most outer twines will break first. When the outer twines break the second-most outer twines will become the outer twines and will break subsequently.

A schematic baling machine according to an embodiment of the invention is shown in FIGS. 4a and 4b . This machine is similar in many respects to the prior art machine shown in FIGS. 1, 2 a and 2 b and the foregoing description therefore applies in part also to this machine. As in the prior art machine, the side walls 4 (not shown in FIGS. 4a and 4b ) include adjustable wall sections, each adjustable wall section being mounted for pivoting movement about a pivot joint at the upstream edge of the wall section. An adjuster device is connected to each wall, the adjuster device being operable to adjust the position of the wall and thereby to adjust the frictional force applied to the already-formed bale 20 as it moves through the baling chamber 2. Alternatively or in addition, the adjuster devices may be configured to adjust the positions of the top and/or bottom walls of the baling chamber. The adjuster devices may for example be hydraulically or electrically driven and are controlled by a control device, which can operate automatically or in response to control signals provided by the operator.

According to the invention, a twine loop increasing roller/guide 41 is provided to be engageable with the outermost twine loops 22, where it can be either fixed or adjusted to a position that increases the twine loop length by causing the binding device at that location to spool out more twine to a desired length before a knot 40′ is tied, compared to the innermost loops. FIGS. 4a to 4d show different possible positions so as to increase the loop length from nothing as shown in 4 a to a maximum as shown in 4 d. The roller may be fixed in any of the positions of FIGS. 4b to 4c or adjustable between these options. Meanwhile, twine loops on the inward part of the bale can be formed in a conventional manner where no additional length needs to be applied.

Control over the twine loop length is preferably adjustable so as to adapt the process to the expansion properties of the bale material, where expansion affects mostly on the outermost sides. For relatively inelastic materials that expand only slightly after compaction (e.g. silage), the required increase will be small (e.g. FIG. 4b ), whereas for more elastic materials that tend to expand a lot after compaction (e.g. dry straw and/or materials that are baled in very dry conditions) the required increase will be substantial (e.g. 5-10 cm at compression levels of 6-10 bar, e.g. 4 c or 4 d).

FIGS. 5a and 5b illustrate a cross section of a loop extending mechanism according to the invention located at the outer edges of where a bale is to be formed. A roller 41 is arranged to move to a number of different positions 41′, 41″ which, in practice, causes more twine to be drawn from a spool (not shown) before a knot is tied to secure the twine about a circumference of the bale 20. As mentioned, the extent of the lengthened position is determined by the material or other environmental conditions either sensed automatically or activated by manual input settings.

The configuration of the invention described is intended to extend the peripheral or outermost twine loops of the bale, compared to the inner twines (e.g. of the five twine loops 22 across the bale in the illustrated prior art FIG. 2, the outermost would amount to the first and fifth loops, whereas the third is the innermost), to the same extended length in order to account for additional compression at the outer sides. However, the invention could be configured to provide different twine loop lengths across the same bale if this were desirable. In other words a series of rollers 41 could move independently of one another. In the preferred form the outermost twine loops (on the left and right sides of the bale respectively) are adjusted to have greater loop length, but the next most outer twine loops (say the second and fourth loops referring to FIG. 2) could also be adjusted, perhaps to a lesser extent. Of course the same principle could be applied to balers with more than 3 twine loops.

Although the description is based on a double tie knotter (knotting two knots 40 and 40′ in the loop) the principle of adjustment of the twine loop length will also be effective on a single tie knotter baler (with only knot 40′ in the loop). 

The invention claimed is:
 1. A baler apparatus comprising: a baling chamber including a channel including an inlet end and an outlet end and at least one adjustable wall adjusting compression of a body of bale material by controlling pressure applied to the body of bale material during formation of a bale; a reciprocating plunger adjacent the inlet end of the baling chamber operable to compress a body of bale material within the baling chamber; a binding device configured for binding the compressed body of bale material to form a bale by use of twine loops; and an extension device configured for extending a length of outermost twine loops at binding of the bale to be greater than a length of innermost twine loops, to reduce compression within an outer part of the body of bale material.
 2. The baler apparatus of claim 1, wherein the extension device extends the length of the outermost twine loops in response to factors including type of bale material and environmental conditions.
 3. The baler apparatus of claim 1, wherein the extension device includes a roller or guide.
 4. The baler apparatus of claim 3, wherein the roller or guide is locatable for engagement against an outside of one of the twine loops.
 5. The baler apparatus of claim 3, further comprising a twine guide guiding the twine over the roller or guide.
 6. The baler apparatus of claim 3, wherein the roller or guide is located adjacent a knotting device.
 7. The baler apparatus of claim 1, wherein the binding device is configured to close each of the twine loops with one single knot.
 8. The baler apparatus of claim 1, wherein the binding device is configured to close each of the twine loops with two knots.
 9. The baler apparatus of claim 1, wherein the extension device is configured to independently vary a length of individual twine loops per twine loop.
 10. The baler apparatus of claim 1, wherein an extra loop length increase of the outermost twine loops is 1-3 cm relative to the innermost twine loops.
 11. The baler apparatus of claim 1, wherein the extension device also increases second outermost twine loops by 1-2 cm relative to the innermost twine loops.
 12. The baler apparatus of claim 1, wherein the extension device is configured to increase loop length of a twine by up to 25 cm from its regular length.
 13. The baler apparatus of claim 1, wherein the extension device is removable or displaceable.
 14. The baler apparatus of claim 1, wherein the extension device is fixedly but adjustably connected to the baler.
 15. The baler apparatus of claim 1, wherein the increase of the length of the outermost twine loops is achieved by positioning a knotting device relatively further or at an adjustable distance from the bale when the outermost twine loops are formed.
 16. A method of baling bale material in a baler apparatus including a baling chamber including a channel having an inlet end and an outlet end and at least one adjustable wall adjusting compression of a body of bale material by controlling pressure applied to the body of bale material during formation of a bale, a reciprocating plunger adjacent the inlet end of the baling chamber, and a binding device, the method comprising: activating the reciprocating plunger to compress the body of bale material in the baling chamber; and binding the compressed body of the bale material with twine loops to form a bale, wherein the binding includes using an extension device to extend a length of outermost twine loops to be greater than a length of innermost twine loops around the compressed bale material, at least during closing of a loop, to form the bale and reduce compression within an outer part of the bale.
 17. The baler apparatus of claim 1, wherein the extension device includes a plurality of rollers and each roller of the plurality of rollers is configured to adjust a length of a respective twine loop independently from lengths of the other twine loops. 